This invention relates to a system and a method for supplying air to a fuel cell and more particularly, to a system and method which uses the potential energy stored within hydrogen gas that is supplied to a vehicle""s fuel cell to drive a compressor which pressurizes and delivers air to the fuel cell, thereby improving the efficiency and the fuel economy of the vehicle.
In order to reduce automotive emissions and the demand for fossil fuel, automotive vehicles have been designed that are powered by electrical devices such as fuel cells. These fuel cell-powered electric vehicles reduce emissions and the demand for conventional fossil fuels by eliminating the internal combustion engine (e.g., in completely electric vehicles) or by operating the engine at only its most efficient/preferred operating points (e.g., in hybrid electric vehicles).
Many fuel cells consume hydrogen gas and air (e.g., as a constituent). The consumed hydrogen and air must be properly stored and transferred to the fuel cell at certain pressures in order to allow the fuel cell and vehicle to operate in an efficient manner.
Vehicles employing these types of fuel cells often include systems and/or assemblies for storing and transmitting hydrogen gas and air to the fuel cell. Particularly, the hydrogen gas is typically stored within a tank at a relatively high pressure and with a relatively high amount of potential energy. The hydrogen gas is then transferred to the fuel cell by use of several conduits and several pressure-reducing regulators which lower the pressure of the gas by a desirable amount. While the pressure of the hydrogen gas leaving the fuel tank is substantially lowered prior to entering the fuel cell, it remains above normal atmospheric pressures which is required for efficient operation. The air that is communicated to the fuel cell is obtained at atmospheric pressures and must be pressurized or otherwise driven through the system in order to ensure proper and efficient fuel cell operation. This pressurization and/or driving of air through the system is typically performed by use of one or more compressors or turbines. These compressors or turbines require electrical energy for their operation, and therefore drain the vehicle""s battery and use generated electrical energy, which could otherwise be used to power the vehicle""s electrical components and accessories.
There is therefore a need for a new and improved system and method for use with a fuel cell-powered vehicle which utilizes the potential energy stored within the vehicle""s hydrogen gas supply to drive an air compressor which supplies air to the fuel cell, thereby reducing the power requirements of the vehicle and improving fuel economy.
A first non-limiting advantage of the invention is that it provides a system and method for supplying air to a fuel cell which utilizes the potential energy of compressed gas stored within a vehicle to supply pressurized air to the vehicle""s fuel cell.
A second non-limiting advantage of the invention is that it efficiently supplies air to a fuel cell by converting the potential energy of stored hydrogen gas into mechanical energy which is used to drive a compressor.
According to a first aspect of the present invention, a system is provided for supplying air to a fuel cell within a vehicle. The system includes a fuel tank which stores pressurized hydrogen gas; a first conduit system which selectively and fluidly couples the fuel tank to the fuel cell, effective to allow the hydrogen gas to be selectively communicated to the fuel cell; an expander which is disposed within the first conduit system and which is selectively and rotatably driven by the pressurized hydrogen gas, effective to lower the pressure of the hydrogen gas which is communicated to the fuel cell; a second conduit system which selectively and fluidly couples the fuel cell to a source of air, effective to allow the air to be selectively communicated to the fuel cell; and a compressor which is disposed within the second conduit system and which is mechanically coupled to and rotatably driven by the expander, the compressor being effective to compress the air which is communicated to the fuel cell.
According to a second aspect of the present invention, a method is provided for delivering pressurized gas and air to a fuel cell. The method includes the steps of: storing the pressurized gas within a container; providing a first conduit system for transferring the pressurized gas from the container to the fuel cell; providing a second conduit system for transferring air to the fuel cell; providing an expander; providing a compressor; operatively disposing the expander within the first conduit system; operatively disposing the compressor within the second conduit system; operatively connecting the expander to the compressor; and channeling the pressurized gas through the expander, effective to rotatably drive the expander and the compressor, thereby reducing the pressure of the gas that is transferred to the fuel cell and increasing the pressure of the air that is transferred to the fuel cell.
These and other features, aspects, and advantages of the invention will become apparent by reading the following specification and by reference to the following drawings.